Journal of Applied Physiology, Vol 81, Issue 3 1249-1254, Copyright © 1996 by American Physiological Society

ARTICLES

Exercise hyperpnea and hyperthermia in humans

M. D. White and M. Cabanac
Department of Physiology, Faculty of Medicine, Laval University, Quebec, Canada.

The problem of the relative hyperpnea occurring at high levels of exercise remains unresolved. This study examined whether the hyperpnea observed in humans during exercise at approximately 70% of maximal work capacity was related to cranial (tympanic) and thoracic (esophageal) temperatures. Six trained male subjects pedaled at approximately 60 revolutions/min on an electrically braked cycle ergometer in a climatic chamber at 25 degrees C and approximately 35% relative humidity in two sessions. The subjects pedaled until exhaustion in two sessions. In one session work rate was increased by 40 W every 2 min and in the other session by 20 W every 2 min. In both exercise sessions, core temperature thresholds for ventilation were evident and subsequently tympanic and esophageal temperatures diverged. This suggested that the hyperpnea in humans observed after approximately 70% of an individual's maximal work rate was determined, in part, by core temperatures and revealed supportive evidence for selective brain cooling in humans.

This article has been cited by other articles:

				N. Fujii, Y. Honda, K. Hayashi, H. Soya, N. Kondo, and T. Nishiyasu Comparison of hyperthermic hyperpnea elicited during rest and submaximal, moderate-intensity exercise J Appl Physiol, April 1, 2008; 104(4): 998 - 1005. [Abstract] [Full Text] [PDF]

				S. K. Maloney, D. Mitchell, G. Mitchell, and A. Fuller Absence of selective brain cooling in unrestrained baboons exposed to heat Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2007; 292(5): R2059 - R2067. [Abstract] [Full Text] [PDF]

				A. L. Chu, O. Jay, and M. D. White The effects of hyperthermia and hypoxia on ventilation during low-intensity steady-state exercise Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R195 - R203. [Abstract] [Full Text] [PDF]

				M. D. White Components and mechanisms of thermal hyperpnea J Appl Physiol, August 1, 2006; 101(2): 655 - 663. [Abstract] [Full Text] [PDF]

				D. Robertshaw Mechanisms for the control of respiratory evaporative heat loss in panting animals J Appl Physiol, August 1, 2006; 101(2): 664 - 668. [Abstract] [Full Text] [PDF]

				K. Hayashi, Y. Honda, T. Ogawa, N. Kondo, and T. Nishiyasu Relationship between ventilatory response and body temperature during prolonged submaximal exercise J Appl Physiol, February 1, 2006; 100(2): 414 - 420. [Abstract] [Full Text] [PDF]

				B. J. Holtzclaw Circadian Rhythmicity and Homeostatic Stability in Thermoregulation Biol Res Nurs, April 1, 2001; 2(4): 221 - 235. [Abstract] [PDF]

				Z. Mariak, M. D. White, J. Lewko, T. Lyson, and P. Piekarski Direct cooling of the human brain by heat loss from the upper respiratory tract J Appl Physiol, November 1, 1999; 87(5): 1609 - 1613. [Abstract] [Full Text] [PDF]

				P. L. Entin, D. Robertshaw, and R. E. Rawson Thermal drive contributes to hyperventilation during exercise in sheep J Appl Physiol, July 1, 1998; 85(1): 318 - 325. [Abstract] [Full Text] [PDF]